Method of selecting plurality of sets of optimal beam pairs in wireless communication system

ABSTRACT

The present disclosure provides a method of selecting a plurality of sets of optimal beam pairs in a wireless communication system. The method includes estimating channels associated with a plurality of transmit ports for each receive port from a plurality of receiver ports. Further, the method includes selecting the plurality of optimal transmit and receive beam pairs using average power level computation and capacity maximization techniques.

PRIORITY

This application claims priority under 35 U.S.C. § 119(a) to IndianPatent Applications filed in the Indian Patent Office on Jan. 16, 2017and assigned Serial No. 201741001716 (PS), and filed on Jan. 15, 2018and assigned Serial No. 201741001716 (CS), the entire disclosure of eachof which is incorporated herein by reference.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates in general to wireless communications,and more particularly to a method and system for selecting a pluralityof sets of optimal transmit beam and receive beam pairs in a wirelesscommunication system.

2. Description of the Related Art

Millimeter wave beamforming is one of the key technologies for 5Gcommunications. The large swathes of bandwidth at these frequenciesenable high data rate communication. Beamforming is required in such 5Gcommunication systems to compensate for the significantly higher pathloss. Transmit beamforming using directional beam-patterns focuses thetransmit signal in one of the possible spatial directions. Similarly, inreceive beamforming, the receive beams facilitate directionalselectivity of the received signals.

In a beam-formed system the optimal transmit and receive beams needs tobe determined for reliable communication. In a single input singleoutput (SISO) system, a single transmit beam and receive beam pair needsto be estimated for a single stream transmission. In a multi-input andmulti-output (MIMO) system, multiple transmit beam and receive beampairs for the multiple streams need to be estimated. A beam setcomprises of such multiple beam-pairs. A plurality of such sets need tobe estimated with the objective of reliable communication in thepresence of beam blockages and misalignments. This is performed usingbeam-training mechanisms. The beam-training mechanisms require areceiver to reliably estimate optimal beams (directionality) from a setof possible beams in a face of fading, interference and noise.

Evolving 5G specifications will need incorporation of periodic and aperiodic beam-control signaling along with data transmission to estimateand track the beam-pairs associated with the base station (BS) and userequipment (UE). In one of the 5G specifications, these are calledbeam-reference signals (BRS). The other signals that are typically usedfor beam training are the synchronization signals (SS) and channel stateinformation reference signals (CSI-RS),

There exists methods in which optimal transmit beam and receive beampairs are selected using both capacity maximization and powermaximization. However, the methods in the prior art when adapted towardshigher configurations of number of antennas and beams results inunmanageable complexity which therefore makes the selection of theoptimal beam pairs extremely difficult for practical implementation.Also the performance of the existing methods is affected in the presenceof interference, blockages and misalignments.

Therefore, a need exists to provide solution for the above mentionedproblem or other shortcomings or at least provide a useful alternative.

SUMMARY

The principal object of the embodiments herein is to provide a method ofselecting a plurality of sets of optimal or best transmit beam andreceive beam pairs in a wireless communication system.

Another object of the embodiments herein is to determine the pluralityof sets of optimal transmit beam and receive beam pairs using a CapacityMaximization (CM) technique on a reduced search space obtained from apower maximization method.

Another object of the embodiments herein is to identify at least onetransmit and receive beam ID pairs by traversing diagonally across amatrix, wherein at least one beam ID pair is anchored. A scan over overat least one beam ID pair in the matrix is performed using the anchoredat least one beam ID pair to identify one or more beam ID pairs.

Accordingly embodiments herein provide a method of selecting a pluralityof sets of optimal transmit beam and receive pairs in a wirelesscommunication system. The method includes estimating, by a receiver,channels associated with a plurality of transmit ports for each receiveport from a plurality of receive ports. Further, the proposed methodincludes determining, by the receiver, the plurality of optimal transmitbeam and receive beam pairs using: average power level at each receiveport for at least one transmit port based on the estimated channelassociated between the transmit beam and receive beam pairs, a set offirst power matrices where each first power matrix, from the set offirst power matrices, comprises at least one transmit port, transmitbeam ID and receive beam ID pairs associated with each receive port,where the set of first power matrices is formed based on the averagepower level at each of the receive port, and a second capacity matrixformed based on capacity maximization obtained from the set of firstpower matrices, wherein the plurality of sets of optimal transmit beampairs and receive beam pairs associated with the each of the transmitand receive ports is selected from the second capacity matrix.

In an embodiment, where the average power level at each receiver portfor at least one transmit port based on the estimated channel associatedbetween the transmit beam and receive beam pairs comprises computing theaverage power level at each receive port for at least one transmit portbased on the estimated channel, and determining that the average powerlevel of each receive port for at least one transmit port meets a powerlevel threshold.

In an embodiment, where the capacity maximization obtained from the setof first power matrices is determined based on one of maximizing aSignal-to-Interference plus noise ratio (SINR) and a logarithmicfunction of SINR (capacity) associated with the one or more sets oftransmit beam and receive beam pairs associated with the plurality ofreceive antenna ports.

In an embodiment, where one or more sets of capacity maximizing beampairs comprises of a number of elements where each element is associatedwith a transmit port number, a receive port number, a transmit beam IDand a receive beam ID.

In an embodiment, where determining the plurality of optimal transmitbeam pairs and receive beam pairs comprises: identifying at least onetransmit beam ID and receive beam ID pairs by traversing diagonallyacross a third matrix, anchoring the at least one transmit beam ID andreceive beam ID pairs identified in the third matrix, performing a scanover at least one transmit beam ID and receive beam ID pairs in thethird matrix using the at least one anchored transmit beam ID andreceive beam ID pairs, and determining the plurality of sets of optimaltransmit beam pairs and receive beam pairs based on the scan over the atleast one anchored transmit beam ID and receive beam ID pairs.

In an embodiment, the third matrix is determined based on the estimatedchannels associated with at least one transmit port from the pluralityof transmit ports associated with each receive port from the pluralityof receive ports.

Accordingly embodiments herein provide a method of selecting a pluralityof sets of optimal transmit beam pairs and receive beam pairs in awireless communication system. The method includes estimating, by areceiver, channels associated with a plurality of transmit ports foreach receive port from a plurality of receive ports, and determining, bythe receiver, the plurality of sets of optimal transmit beam and receivebeam pairs by: identifying at least one transmit beam ID and receivebeam ID pairs by traversing diagonally across a first matrix, anchoringthe at least one transmit beam ID and receive beam ID pairs identifiedin the first matrix, performing a scan over at least one transmit beamID and receive beam ID pairs in the first matrix using the at least oneanchored transmit beam ID and receive beam ID pairs, and determining theplurality of sets of optimal transmit beam pairs and receive beam pairsbased on the scan over the at least one anchored transmit beam ID andreceive beam ID pairs.

In an embodiment, where the first matrix is determined based on theestimated channel associated with a plurality of transmit ports for eachreceive port from a plurality of receiver ports and the associatedtransmit beam and receive beam pairs.

In an embodiment, the at least one set of optimal transmit beam andreceive beam pairs from the plurality of sets of optimal transmit beamand receive beam pairs comprises of a number of elements where eachelement is associated with a transmit port number, a receive portnumber, the transmit beam ID and the receive beam ID pairs

Accordingly embodiments herein provide a receiver for selecting aplurality of optimal beam pairs in a wireless communication system. Thereceiver includes a memory, a processor coupled to the memory, and abeam pair selector coupled to the processor. The beam pair selector isconfigured to estimate channels associated with a plurality of transmitports for each receive port from a plurality of receiver ports fortransmit beam and receive beam pairs, determine the plurality of sets ofoptimal transmit beam and receive beam pairs using: average power levelat each receive port for at least one transmit port based on theestimated channel associated between the transmit beam and receive beampairs, a set of first power matrices where each first power matrix, fromthe set of power matrices, comprises at least one transmit port,transmit beam ID and receive beam ID pairs associated with each receiveport, wherein the set of first power matrices is formed based on theaverage power level at each of the receive port, and a second capacitymatrix formed based on capacity maximization obtained from the set offirst power matrices, wherein the plurality of sets of optimal transmitbeam pairs and receive beam pairs associated with each of the transmitand receive ports is selected from the second capacity matrix.

Accordingly embodiments herein provide a receiver for selecting aplurality of optimal beam pairs in a wireless communication system. Thereceiver includes a memory, a processor coupled to the memory, and abeam pair selector coupled to the processor. The beam pair selector isconfigured to estimate channels associated with a plurality of transmitports for each receive port from a plurality of receive ports, anddetermine the plurality of sets of optimal transmit beam and receivebeam pairs by: identify at least one transmit beam ID and receive beamID pairs by traversing diagonally across a first matrix, anchor the atleast one transmit beam ID and receive beam ID pairs identified in thefirst matrix, perform a scan over at least one transmit beam ID andreceive beam ID pairs in the first matrix using the at least oneanchored transmit beam ID and receive beam ID pairs, and determine theplurality of sets of optimal beam transmit beam pairs and receive pairsbased on the scan over the at least one anchored transmit beam ID andreceive beam ID pairs.

These and other aspects of the embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingpreferred embodiments and numerous specific details thereof, are givenby way of illustration and not of limitation. Many changes andmodifications may be made within the scope of the embodiments hereinwithout departing from the spirit thereof, and the embodiments hereininclude all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

This method is illustrated in the accompanying drawings, throughoutwhich like reference letters indicate corresponding parts in the variousfigures. The embodiments herein will be better understood from thefollowing description with reference to the drawings, in which:

FIG. 1A illustrates a schematic overview of a beam-training mechanism,according to a prior art as disclosed herein.

FIG. 1B illustrates a schematic overview of a plurality of sets ofdirectional links between a transmitter and a receiver in a wirelesscommunication system, according to a prior art as disclosed herein.

FIG. 2 is a block diagram illustrating various hardware components ofthe receiver, according to an embodiment as disclosed herein;

FIG. 3 is a block diagram illustrating various hardware components ofthe power and capacity computational unit of the receiver, according toan embodiment as disclosed herein;

FIG. 4 is a block diagram illustrating various hardware components ofthe transmitter port selection unit of the receiver, according to anembodiment as disclosed herein;

FIGS. 5A-5B are flow diagrams illustrating a method of selecting beam IDpairs associated with a transmitter antenna array and a receiver antennaarray, according to an embodiment as disclosed herein;

FIG. 6 illustrates a matrix for selecting a plurality of set of optimalbeam ID pairs, according to a prior art as disclosed herein;

FIG. 7 illustrates a matrix for selecting a plurality of set of optimalbeam ID pairs, according to an embodiment as disclosed herein; and

FIG. 8 is a graph representing a probability of correct detectioncomparison of the hybrid power and capacity maximization scheme with thereceived signal strength based scheme in presence of interference,according to an embodiment as disclosed herein.

DETAILED DESCRIPTION

Various embodiments of the present disclosure will now be described indetail with reference to the accompanying drawings. In the followingdescription, specific details such as detailed configuration andcomponents are merely provided to assist the overall understanding ofthese embodiments of the present disclosure. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the present disclosure. Inaddition, descriptions of well-known functions and constructions areomitted for clarity and conciseness.

Also, the various embodiments described herein are not necessarilymutually exclusive, as some embodiments can be combined with one or moreother embodiments to form new embodiments. Herein, the term “or” as usedherein, refers to a non-exclusive or, unless otherwise indicated. Theexamples used herein are intended merely to facilitate an understandingof ways in which the embodiments herein can be practiced and to furtherenable those skilled in the art to practice the embodiments herein.Accordingly, the examples should not be construed as limiting the scopeof the embodiments herein.

As is traditional in the field, embodiments may be described andillustrated in terms of blocks which carry out a described function orfunctions. These blocks, which may be referred to herein as units ormodules or the like, are physically implemented by analog and/or digitalcircuits such as logic gates, integrated circuits, microprocessors,microcontrollers, memory circuits, passive electronic components, activeelectronic components, optical components, hardwired circuits and thelike, and may optionally be driven by firmware and/or software. Thecircuits may, for example, be embodied in one or more semiconductorchips, or on substrate supports such as printed circuit boards and thelike. The circuits constituting a block may be implemented by dedicatedhardware, or by a processor (e.g., one or more programmedmicroprocessors and associated circuitry), or by a combination ofdedicated hardware to perform some functions of the block and aprocessor to perform other functions of the block. Each block of theembodiments may be physically separated into two or more interacting anddiscrete blocks without departing from the scope of the disclosure.Likewise, the blocks of the embodiments may be physically combined intomore complex blocks without departing from the scope of the disclosure.

Accordingly embodiments herein provide a method of selecting a pluralityof sets of optimal beam pairs from a plurality of beam pairs in awireless communication system. The proposed method includes estimating,by a receiver, a channel associated with at least one transmit port froma plurality of transmit ports associated with each receive port from aplurality of receiver ports for all transmit beam and receive beampairs. Further, the proposed method includes determining, by thereceiver, the sets of optimal beam pairs using an average power level ofeach receiver port for the at least one transmit port based on theestimated channel, a first matrix comprising the at least one transmitport and beam ID pairs associated with each receive port, wherein thefirst matrix is formed by processing each OFDM symbol based on the powerlevel of each receiver port, and a second matrix formed based on atleast one capacity and SINR associated with each beam ID pair obtainedfrom a plurality of first matrices, wherein the plurality of sets ofoptimal transmit beam and receive beam pair is selected based on thesecond matrix. Accordingly embodiments herein provide a method ofselecting a plurality of optimal transmit and receive beam pairs in awireless communication system. The proposed method includes estimating,by a receiver, a channel associated with a plurality of transmit portsfor each receive port from a plurality of receiver ports. Further theproposed method includes determining, by the receiver, the optimal beampair by identifying, by the receiver, at least one beam ID pair bytraversing diagonally across a first matrix, anchoring, by the receiver,the at least one beam ID pair identified in the first matrix,performing, by the receiver, a scan over at least one beam ID pair inthe first matrix using the anchored at least one beam ID pair, anddetermining, by the receiver, the plurality of optimal beam pairs basedon the scan over the at least one anchored beam ID pair.

Unlike to conventional methods and systems, the proposed method can beused to reduce a complexity for practical implementation by using anintelligent combination of both a capacity maximization (CM) and areceived power maximization (PM) techniques without compromising on theperformance while identify the one or more sets of optimal transmit andreceive beam pairs.

Referring now to the drawings, and more particularly to FIGS. 1 through8, these are shown as preferred embodiments.

FIG. 1A illustrates a schematic overview of an exemplary beam-trainingscheme, according to a prior art as disclosed herein.

In an embodiment, the proposed embodiments can also be applicable toother beam-training methods.

In downlink Multiple Input Multiple Output-Orthogonal Frequency DivisionMultiplexing (MIMO-OFDM) based communication system includes atransmitter (Tx) and a receiver (Rx) which can be, but not limited to, aBase Station (BS), a UE, a mobile station (MS), etc. The transmitterincludes N_(T) transmit antenna ports connected to antenna arrayscomprising of N^(RF) _(T) antennas via phase shifters. Similarly, thereceiver includes N_(R) receive antenna ports connected to antennaarrays with N^(RF) _(R) antennas. The number of data streams N_(s) thatcould be transmitted simultaneously is limited by the number of RFchains at the transmitter and receiver, Ns≤min{N_(T),N_(R)}. Hence thenumber of elements in each of the plurality of sets of best transmitreceive beam pairs is limited by N_(S).

The exemplary transmitter generates Beam Reference Signal (BRS) andsub-frame(s) (SF) of BRS are transmitted once every 5 ms comprising ofN_(SF)=14 OFDM symbols. Each BRS are placed in the 1^(st) and 25^(th)sub-frames of the 10 ms radio frame comprising of 50 SFs.

In each BRS sub-frame, the OFDM symbols are generated in the followingmanner. Initially, Quadrature Phase Shift Keying (QPSK) modulation isperformed on BRS sequences, r_(l)(m), where l and m vary as, (l=0, 1, .. . , N_(SF)−1), (m=0, 1, . . . , Nc=8[N^(DL) _(RB)−18]−1), and N^(DL)_(RB)=100 are generated from a pseudo-random sequence, where N_(C) isthe length of the BRS sequence. The BRS sequences are a function of theOFDM symbol index 1 and the cell-ID N^(cell) _(ID).

Consider r_(l)=[r_(l)(m)|m=0, 1, . . . , Nc−1]^(T) be the BRS sequencevector for the l^(th) OFDM symbol. The BRS sequences r_(l)(m) are thenmapped to modulation symbols t^(p) _(l)(k), which is a BRS symbolassociated with the p^(th) antenna port, where (p=0, 1, . . . ,N_(T)−1), and the l^(th) OFDM symbol on the k^(th) subcarrier. Lett_(l)(k)=[t^(p) _(l)(k), |p=0, 1, . . . , N_(T)−1] be the correspondingvector.

The number of transmit antenna ports to N_(T)=8. The BRS symbols aregiven by:

t _(l) ^(p)(k)=g _(p) (m′)rl(m)  (1)

Here, g _(p) (m′), m′=m N_(T) is an antenna port specific cover sequencedrawn from the p^(th) row of an N_(T)×N_(T) Hadamard matrix G. k=N^(RB)_(sc)k′+k″, N^(RB) _(sc)=12 is the sub-carrier index for the modulatedsymbols, where (k″=4, . . . N_(SF)−1) and (k′=0, 1, . . . , [½(N^(DL)_(RB)−18)]−1, [½(N^(DL) _(RB)+18)], [½(N^(DL) _(RB+)18)]+1, . . . ,N^(DL) _(RB)−1).

The frequency domain BRS symbols t_(l) ^(p)(k) are OFDM modulated toobtain {tilde over (t)}^(p) _(l)(n) as follows

$\begin{matrix}{{{\overset{\sim}{t}}^{p_{1}}(n)} = {\frac{1}{\sqrt{NFFT}}{\sum\limits_{K = 0}^{{NFFT} - 1}{{t_{l}^{p}(k)}e^{j\;}\frac{2\pi \; {nk}}{NFFT}}}}} & (2)\end{matrix}$

{tilde over (t)}^(p) _(l)(n) is cyclic prefixed (CP) to obtain t^(p)_(l)(n) which is the n^(th) sample of the l^(th) OFDM symbol associatedwith the p^(th) antenna port. Let t_(l)(n)=[t⁰ _(l)(n), t¹ _(l)(n), . .. , t_(l) ^(NT-1)(n)] be the vector of samples at the n^(th) timeinstant that are fed to the N_(T) RF chains, from the l^(th) OFDMsymbols. The beam formed output vector t_(l)(n) can be represented as

t′ _(l)(n)=W _(l) t _(l)(n)  (3)

Here, W_(l) is an N_(T)N^(RF) _(T)×N_(T) analog beam-forming matrix witha block diagonal structure given by

W _(l)=diag{a _(t)*(∅_(o)),a _(t)*(∅_(l)), . . . ,a_(t)*(∅_(NT-1))}  (4)

where a_(t)*(∅i) with dimensions N^(RF) _(T)×1, corresponds to theanalog steering vector for the i^(th) transmit array antenna (i=0, 1, .. . , N_(T)−1). ∅i is the azimuth steering angle from the antennaboresight corresponding to the analog beam former of the array antennaconnected to the i^(th) RF chain. The elements of a_(t)*(∅i) aredependent on the array geometry and without loss of generality, only 2-Dbeamforming (linear array) is considered for simplicity. The techniquesand results which are presented is applicable to arbitrary antennaarrays. The baseband precoding is not applied on the BRS symbols asbased band precoding are used to estimate the analog RF beams only. TheW_(l) can be expressed as

$\begin{matrix}{W_{l} = \begin{bmatrix}{a_{t}^{*}\left( \varphi_{0} \right)} & 0_{N_{T}^{RF}} & \ldots & 0_{N_{T}^{RF}} \\0_{N_{T}^{RF}} & {a_{t}^{*}\left( \varphi_{1} \right)} & \ldots & 0_{N_{T}^{RF}} \\\vdots & \vdots & \ddots & \vdots \\0_{N_{T}^{RF}} & 0_{N_{T}^{RF}} & \ldots & {a_{t}^{*}\left( \varphi_{N_{T} - 1} \right)}\end{bmatrix}} & (5)\end{matrix}$

Each a_(t)*(∅i) can take on a discrete set of possible values such asnumber of transmitter beams (N_(TxB)), depending on the quantizedbeamforming codebook design. Each set corresponds to a beam which ischaracterized by the antenna port number P_(i) and the beam index(beam-ID) B_(j) at the transmitter which is represented as T(P_(i),B_(j)).

$\begin{matrix}\left. {a_{t}^{*}\left( Ø_{i} \right)}\leftrightarrow{{T\left( {P_{i},B_{j}} \right)}\begin{matrix}{{i = 0},1,\ldots \mspace{14mu},{N_{T} - 1}} \\{{j = 0},1,\ldots \mspace{14mu},{N_{T \times B} - 1}}\end{matrix}} \right. & (6)\end{matrix}$

At the receiver side, a mapping of a transmit beam index to an OFDMsymbol in the BRS is obtained. The analog beams remain unchanged duringone OFDM symbol duration. The time taken to transmit all the distinctbeams is characterised by the beam transmission period (TBTP) denoted byΔt. This is illustrated in FIG. 1A with an example. T (P_(m),B_(n)),W_(l) and a_(t)*(∅i) in (4) and (6) remain unchanged for the duration ofthe transmitted OFDM symbol and changes from symbol to symbol in the BRSsub-frames within every TBTP. In this way, the scheme sweeps across themaximum number of transmit beam training opportunities available.

At the receiver side, the transmitted signal passes through themillimeter wave channel and reaches each receiver RF chain. The CPportion of the signal is removed. The received signal y_(l)(k) withdimensions N_(R)×1 in the presence of additive white Gaussian noise(AWGN) on the k^(th) subcarrier can be expressed as

Yl(k)=V ^(T) _(l) H _(l)(k)W _(l) t _(l)(k)+V ^(T) _(l) n(k)  (7)

H_(l)(k) is an (N_(R)N^(RF) _(R)×N_(T)N^(RF) _(T)) frequency domain fullchannel matrix of the l^(th) OFDM symbol for the k^(th) subcarrier. Thechannel model is not presented here for brevity. W_(l) and henceH_(l)(k) change on an OFDM symbol basis as explained earlier.n(k)˜CN(0N_(R)N^(R) _(R) ^(F), σ² _(n)IN_(R)N^(R) _(R) ^(F)) is thenoise vector.

Similar to (4) and (5), V_(l) is the receive analog beamforming phaseshifters expressed as a block diagonal matrix with dimensionsN_(R)N^(RF) _(R)×N_(R).

V _(l)=diag{a _(r)*(∅_(o)),a _(r)*(∅_(l)), . . . ,a_(t)*(∅_(NR-1))}  (8)

where a_(r)*(∅i) with dimensions N^(RF) _(R)×1, corresponds to theanalog steering vector for the i^(th) receive array antenna (i=0, 1, . .. , N_(R)−1) is the steering angle from the antenna boresightcorresponding to the analog beam former of the array antenna connectedto the i^(th) RF chain. Just as in the case of the transmitter, thea_(r)*(∅i) can take a discrete set of values, say number of receiverbeams (N_(RxB)), wherein each set corresponds to a beam which ischaracterised by P_(i) and B_(j). This can be represented asR(P_(q),B_(s)).

$\begin{matrix}\left. {a_{r}^{*}\left( \theta_{i} \right)}\leftrightarrow{{R\left( {P_{i},B_{j}} \right)}\begin{matrix}{{i = 0},1,\ldots \mspace{14mu},{N_{T} - 1}} \\{{j = 0},1,\ldots \mspace{14mu},{N_{R \times B} - 1}}\end{matrix}} \right. & (9)\end{matrix}$

The beam-training protocol is explained at FIG. 1. A single beamformedcommunication link comprises of a channel associated with a pair oftransmit beams T (P_(m),B_(n)) and receive beams R(P_(r),B_(s)) havingan array gain of N^(RF) _(T)N^(RF) _(R). This represents one of the SISOlinks. Let this 4-tuple be represented by A_(i) given by

A _(i) ={T(Pm,Bn),R(Pq,Bs)}  (10)

Here, i is defined as {0, N_(T)N_(R)N_(TxB)N_(RxB)−1}. The time taken atthe receiver to obtain all possible channel measurements of A_(i) isreferred to as the beam training period (RBTP) denoted by Δ_(r). Theobject of the beam-forming protocol is to provide scope at the receiverto facilitate the measurement of these channels so as to decide on theoptimal beam pairs for reliable communication.

The receiver fixes its beam, R(P_(r),B_(s))

a_(r)*(∅_(i)) for the BRS subframes that fall within the duration of Δtand switches to the next receive beam for the next Δt and so on to sweepacross all the beams in the Δr as seen in FIG. 1A. Hence the Δr can beexpressed as Δr=N_(RxB)Δt. All the received OFDM symbols in the BRSsubframes within the Δr, are influenced by the same receive beamR(P_(r),B_(s)).

The objective of beam-selection methods is to estimate T (P_(m),B_(n))

a_(t)*(∅_(m)) and R(Pq,Bs)

a_(r)*(∅_(q)) from the received OFDM symbols y_(l)(k) in the BRSsubframes for reliable communication. a_(t)*(∅_(m)) and a_(r)*(∅_(q))that closely match the channels array response vectors so as to maximizethe array gain and minimize the interference are desirable.

From FIG. 1A, y_(l)(k) provides information of the transmit and receivebeam-ID but does not provide information of the ports. For this, theN_(T)N_(R)N_(TxB)N_(RxB) channel estimates are needed from y_(l)(k).

The effective beamformed channels from all the transmit antenna portsare estimated at each of the received antenna ports. LetY_(l)=[y_(l)(0), y_(l)(1) . . . y_(l)(Nc−1)] be a N_(R)×N_(C) matrixformed from the received BRS symbols of the lth OFDM symbol. N_(C) isthe length of the BRS sequence. The combined BRS received symbols of thetransmit ports are separated from each other using a decoveringoperation on a per OFDM symbol basis to obtain the channel estimate asshown below:

Ĥ ^(T) _(l)({acute over (k)})=Gr _(l) [m:n]1N _(T) Y ^(T) _(l)[:,m:n]  (11)

Where m and n are given by

m={acute over (k)}N _(T) , n=m+N _(T)−1

{acute over (k)}=0,1, . . . ,N _(h)−1  (12)

Here, Ĥ^(T) _(l)({acute over (k)}) has dimensions N_(R)×N_(T) where eachelement corresponds to the channel estimate with its associated A_(i).N_(h)=N_(C)/N_(T) are the number of channel estimation matrices obtainedper OFDM symbol. Improved accuracy can be obtained by averaging theestimates over the channel coherence bandwidth.

The orthogonality property of the Hadamard sequences enable channelestimation of a particular transmit-receive beam pair combination of allthe transmit and receive ports from each received OFDM symbol. Hencefrom one received OFDM symbol, {Ai|i=0, 1, . . . , N_(R)N_(T)} areobtained to estimate such channels. For the duration of Δt,N_(R)N_(T)N_(TxB) channels are obtained for the duration of Δt allN_(R)N_(T)N_(TxB)N_(RxB) channels are obtained at FIG. 1A.

FIG. 1B illustrates a schematic overview of a plurality of sets ofdirectional links 105 between a transmitter antenna array 101 and areceiver 102 in a wireless communication network 100, according to aprior art as disclosed herein.

Consider an example scenario, where transmitter 101 includes transmitterantenna arrays 101 a-101 d connected to transmit antenna ports whichtransmit the plurality of directional links 105 to the receiver antennaarrays 102 a-102 b of the receiver 102 connected receiver antenna ports.The sets of plurality of directional links may include N links, e.g.,including links 105 a-105 d between the transmitter antenna array 101and the receiver antenna array 102.

For example, a BRS, denoted as #7, of the transmitter antenna array 101a may form the directional link 105 a with a BRS, denoted as #2, of thereceiver antenna array 102 a; a BRS, denoted as #6, of the transmitterantenna array 101 b may form the directional link 105 b with a BRS,denoted as #2, of the receiver antenna array 102 b; a BRS, denoted as#3, of the transmitter antenna array 101 c may form the directional link105 c with a BRS, denoted as #6, of the receiver antenna array 102 a; aBRS, denoted as #2, of the transmitter antenna array 101 d may form thedirectional link 105 d with a BRS, denoted as #6, of the receiverantenna array 102 b.

In existing methods, the sets of plurality of directional links 105 maybe determined during the BRS scan performed between the transmitter 101and the receiver 102. Further, one or more sets of directional links areselected from the plurality of directional links 105 for an effectivebeam pair to perform a beamforming diversity communication (i.e., MIMOcommunication). The one or more directional links are selected from theplurality of directional links 105 based on a predefined selectedcriterion.

Candidate sets (set 1, set 2) of N_(s) MIMO streams B_(j) can berepresented as

Bj={A0,A1,ANs−1}  (13)

The problem in beam selection in millimeter-wave MIMO systems is tofind, in some sense, the optimal MIMO streams, as illustrated in FIG.1B. The beam pair ordered set is found as

_(max,N)=[B_(j) |j=0,1, . . . ,N−1]  (14)

Such that

M(B ₀)>M(B ₁), . . . M(B _(N-1))  (15)

Here M(⋅) represents a metric, whose maximization is employed to findthe optimal beams. In (15), M (B₀) is metric associated with the optimalMIMO stream set, M (B₁) is the next optimal and so on. The optimal Nbeam sets are presented to the higher layers which can then be used tocommunicate the transmit beams to the BS.

In (7) the parameter N is configurable and can take {1, 2, 4} or othervalues. The optimal N rather than just a single maximum capacity basedset of beams is needed for multiple reasons. In the event ofbeam-blockages and misalignments, the alternative beams can be used forcommunication albeit with lesser throughput. It also aids the BS inimproved multi-user scheduling at the base station.

One choice of the metric is the received signal strength (RSS). The RSSis synonymously called received power. The RSS on the l^(th) OFDM symbol[S_(l)]_(NR×NT) is computed as follows

$\begin{matrix}{S_{l} = {\frac{1}{N_{h}}{\sum\limits_{k^{\prime} = 0}^{N_{b} - 1}{{{\hat{H}}_{l}\left( k^{\prime} \right)} \circ {{\hat{H}}_{l}^{*}\left( k^{\prime} \right)}}}}} & (16)\end{matrix}$

The optimal N beams based on RSS maximization

_(max,N) _(s) ^(S), finds the N beams at each receive port in descendingorder of the highest power.

_(max,N) ^(S)=arg{max[

_(l)]}  (17)

(l=0, 1, . . . , N_(TxB)N_(RxB)−1). This method of beam selection iseasy to implement. However, it is agnostic to the interferences fromother MIMO streams with their associated beams and also other externalinterference.

A choice of the metric that considers the impact of interfering beams isthe information capacity.

$\begin{matrix}{{I\left( B_{j} \right)} = {\sum\limits_{k = 0}^{N_{c} - 1}{\log_{2}{{I_{N_{R}} + {{{\hat{H}}_{c}\left( {k,B_{j}} \right)}R_{\overset{\_}{tt},k}{{\hat{H}}_{c}^{H}\left( {k,B_{j}} \right)}}}}}}} & (18)\end{matrix}$

Here Ĥ_(C)(k, Bj) is the N_(s)×N_(s) MIMO channel on the k^(th)subcarrier and

$R_{\overset{\_}{tt},k} = {{diag}\left\{ {\frac{{SNR}_{0,k}}{N_{T}},\frac{{SNR}_{2,k}}{N_{T}},\ldots \mspace{14mu},\frac{{SNR}_{{N_{T} - 1},k}}{N_{T}}} \right\}}$

The SNR_(i,k) here includes the array gain (N^(RF) _(T)N^(RF) _(R)) dueto the transmit and receive beamforming. This method is attractive, butinvolves very high computational complexity even for typical values ofthe number of beams and antennas.

The optimal N sets of beam ID pairs is tabulated as below

BP₁ BP₂ . . . BPN_(S) 1 Tx_(i)B_(I)D_(j) Rx_(k)B_(I)D₁ 2 3 . . . N

Parameter Value 0 Value 1 N_(T)-Number of transmitter antenna ports 8 8N_(R)-Number of receiver antenna ports 2 2 Max MIMO Streams 2 2N_(TxBID)-No. of transmitter beam ID 14 28 N_(RxBID)-No. of receiverbeam ID 8 8 Number of Beam-ID pair combinations to 3010561 12042241 besearched for optimal 2 MIMO streams

The exhaustive search complexity is too high even for simpleconfigurations. The typical time constraints from evolving 5Gspecification is less than 0.4 ms. Therefore real time constraints arenot obtained using the existing methods As such, optimal solutions arerequired, with reduced complexity which reducing search space,exploiting sparsity, and provide sub-frame based processing.

FIG. 2 is a block diagram illustrating various hardware components ofthe receiver 102, according to an embodiment as disclosed herein. In anembodiment, the receiver 102 includes a communicator 220, a beam pairselector 230, a processor 240, and a memory 250.

The communicator 220 coupled with antenna 210 (e.g., RF antenna), can beconfigured to communicate with the various other apparatus (not shown)in the wireless communication network 100. In an embodiment, the otherapparatus includes, for e.g., other base stations, mobile stations,remote terminals, the UE, and the like. Further, the communicator 220can be configured to internally communicate with other components of thereceiver 102.

The beam pair selector 230 is communicatively coupled with thecommunicator 220 and the processor 240. The beam pair selector 230 isconfigured to estimate and select the optimal beam ID pairs. The beampair selector 230 includes a power and capacity computational unit 232and a transmitter port selection unit 234.

The power and capacity computational unit 232 is configured to obtain afirst power matrix and a second capacity matrix to determine the optimalbeam pairs associated with transmit and receive ports. The optimal “N”beams of all the transmit antenna array for each receive antenna arraybased on an average power computation and energy thresholding. Further,the optimal “N” capacity or SINR maximizing beams are found from R⁰_(Nt×P) and R¹ _(Nt×P).-The detailed operation of the power and capacitycomputational unit 232 is provided in FIG. 3.

Unlike to conventional methods and systems, the proposed method can beused to provide a robust and reliable estimates of the optimal “N” setsof transmit and receive beam-pairs in MIMO communication systems withreduced complexity. The power and capacity computational unit 232 can beconfigured to determine the sets of optimal beams based on a sub-framebasis using the exhaustive beam-scan information. Thus, by virtue of theproposed method an up-to-date beam-pair information at the end of everyBRS sub-frame can be obtained (as detailed in the FIG. 3).

Unlike to conventional methods and systems, the proposed method can beused to generate and update the first power matrix including the firstpower matrices for each of the receive port (e.g., sets of beam pairsfor all transmit ports per receiver port for OFDM level processing). Asthe first power matrix only comprises the optimal beam pairs determinedbased on average power threshold of each such set of beam pairs meetsthe threshold, the search space required for computing the capacitymaximization beam pairs (resultant from the average power measurementand thresholding) are reduced thereof. Further, the optimal beam pairobtained from the computation of the capacity maximization beam pairs(obtained from the first power matrix) are used to form the secondcapacity matrix, where one or more sets of optimal beam pairs associatedwith the transmit and receive ports is selected from the second capacitymatrix.

The transmitter port selection unit 234 is configured to identify newtransmit ports associated with optimal beams pairs per receiver port. Inan embodiment, the transmitter port selection unit 234 is configured tocompute the average power for each beam pair in the OFDM symbol levelprocessing. The new transmit ports associated with the optimal beamspairs, retrieved from the OFDM symbol computation, are then computed inthe sub-frame level. Further, the optimal beams pairs associated withupdated transmit ports, retrieved from the sub-frame level computation,and are computed to determine the “set of beam ID pairs constituting thecapacity maximization based on the sub-frame level computation. In anembodiment, a third matrix including the set of beam ID pairs perupdated transmit port is created. The detailed operation of identifyingthe optimal set of beam ID pairs from the third matrix is explained inFIG. 4.

Unlike to conventional methods and systems, the proposed method can beused to provide a global optimum of pairs of optimal beams of all theMIMO streams.

The processor 240 performs actions based on the instructions provided bythe beam pair selector 230. The processor 240 can be for e.g., ahardware unit, an apparatus, a Central Processing Unit (CPU). The memory250 includes storage locations to be addressable through the processor240. The memory 250 are not limited to a volatile memory and/or anon-volatile memory. Further, the memory can include one or morecomputer-readable storage media. The memory 250 may include non-volatilestorage elements. For example non-volatile storage elements may includemagnetic hard discs, optical discs, floppy discs, flash memories, orforms of electrically programmable memories (EPROM) or electricallyerasable and programmable (EEPROM) memories. Further, the memory 250 canstore the optimal “P” beam ID pairs which can be used for reliablecommunication (i.e., beamforming transmit and received data signals).

FIG. 3 is a block diagram illustrating various hardware components ofthe power and capacity computational unit 232, according to anembodiment as disclosed herein.

The power and capacity computational unit 232 includes a channelestimation unit 302, an average power computational unit 304, a capacitymaximization computational unit 306, and a beam pair identification unit308.

As detailed in the FIG. 1A, y_(l)(k) gives us all information of thetransmit and receive beam-ID but does not give information of the ports.For this, the N_(T) N_(R) N_(TxB) N_(RxB) channel estimates are neededfrom y_(l)(k). Thus, the effective beam formed channels from all thetransmit antenna ports are estimated at each of the received antennaports (please refer to equations 11 & 12).

Further, from one received OFDM symbol, the channel estimation unit 302is configured to obtain the estimates for {A_(i)|i=0, 1, . . . , N_(R)N_(T)} such channels for the duration of Δt, the channel estimation unit302 obtains N_(R) N_(TxB) N_(RxB) channels and for the duration of Δrall N_(T) N_(R) N_(TxB) N_(RxB) channels are obtained (as detailed inthe FIG. 1A).

The average power computational unit 304 is configured to eliminate lowsignal strength channels from the channels Ai using a power computation.For e.g., from each received “l” OFDM symbol, the average powercomputational unit 304 calculates S_(l) (as in (16).

In an embodiment, the average power computational unit 304 is configuredto compare the S_(l) with a predefined power threshold P_(th). If theS_(l) exceeds P_(th) then the average power computational unit 304populate the transmitter antenna ports in a look up table (LUT) L_(r),0<r≤N_(R)−1 for each receiver antenna port.

In an embodiment, the LUT can be associated with the memory 250. Inanother embodiment, the LUT can be associated with a server remotelyaccessible by the receiver 130 using the wireless network. Each row ofthe LUTs are populated with the indices associated with optimal beam-IDpairs per transmit-receive port. The optimal beam ID pairs are definedas the beam ID pairs having maximum power. The L_(r) can be updated on aper-OFDM basis. The Lr is given as follows:

Lr[t,:]=arg{max_(N) {S _(l) [t,r]}}, r=0,1 . . . ,N _(r-1)

t=0,1 . . . ,N _(T-1)

l=0,1 . . . ,N _(TxB) N _(RxB)−1  (19)

The capacity maximization unit 306 is configured to identify whether theOFDM symbol processing in the BRS sub-frame is over. If the BRSsub-frame processing is high then the capacity maximization unit 306 isconfigured to perform capacity maximization search on the reduced set ofbeam ID pairs characterized by Lr.

In an embodiment, the CM of each beam ID pair will be selected based onthe SINR associated with each beam. For e.g., if the “X” transmit beamand “Y” receive beam pair is considered to be associated with increasedSINR then the “X” transmit beam and “Y” receive beam pair is said to bethe beam pair with a maximum capacity.

In an embodiment, the CM computation unit 306 is configured to updatethe capacity maximization beam pair corresponding to each entry of Lr in(19) and form the second capacity matrix. The directional link Bi can beexpressed as in (13) where

Bi={Aj→Lj[m,n], j=0,1, . . . ,NS−1}  (22)

Here (m=0, 1, . . . , N_(T)−1), (n=0, 1, . . . , N−1). The capacitymaximizing streams of optimal “P” beam pairs can be expressed as

_(max,N)=arg[max_(N){

(B _(i))}], i=0,1, . . . ,(N _(T) N)^(N) ^(s) −1  (23)

The search space over which capacity is maximized is (N_(T)N)^(N) ^(s) .The initial power computation based reduction in the search space makesthe capacity based search space independent of NTxB and NRxB thusreducing the complexity.

The beam pair identification unit 308 is configured to identify the oneor more sets of optimal beam pairs associated with the transmit andreceive ports is selected from the second capacity matrix.

Therefore based on the above method, the search space is reduced from3010261 to 1024.

Parameter Exhaustive Proposed N_(T)-Number of transmitter antenna ports8 8 N_(R)-Number of receiver antenna ports 2 2 Max MIMO Streams 2 2N_(TxBID)-No. of transmitter beam ID 14 14 N_(RxBID)-No. of receiverbeam ID 8 8 Number of Beam-ID pair combinations to 3010561 1024 besearched for optimal 2 MIMO streams

FIG. 4 is a block diagram illustrating various hardware components ofthe transmitter port selection unit 234, according to an embodiment asdisclosed herein. The transmitter port selection unit 234 includes achannel estimation unit 402, an average power computational unit 404, atransmitter port identifier 406, a capacity maximization computationalunit 408.

The channel estimation unit 402 is configured to obtain the estimatesfor {Ai|i=0, 1, . . . , NR NT} such channels for the duration of Δt, thechannel estimation unit 302 obtains NR NTxB NRxB channels and for theduration of Δr all NT NR NTxB NRxB channels are obtained (as detailed inthe FIG. 1A).

The average power computational unit 404 is configured to obtain the newtransmit ports associated with optimal beams pairs per receiver port.The new transmit ports associated with the optimal beams pairs areretrieved from the OFDM symbol computation and then computed in thesub-frame level. In an embodiment, the average power computational unit404 is configured to compute the average power for each beam pair in theOFDM symbol level processing. Further, the optimal beams pairsassociated with updated transmit ports, retrieved from the sub-framelevel computation, and are computed to determine the “P” beam ID pairsconstituting the capacity maximization based on the sub-frame levelcomputation as explained in FIG. 3. In an embodiment, average powercomputational unit 404 is configured to generate the third matrixincluding the “P” beam ID pairs per updated transmit port.

In an embodiment, the transmit port identifier 406 is configured tocontinuously update the third matrix with both new and old transmitterports identified in the BRS sub-frame level.

The capacity maximization computational unit 416 is configured toperform a two stage capacity maximization on the reduced set of beam IDpairs characterized by Lr to identifying the capacity maximizing beam IDpairs

_(max,1) ^(I) with reduced complexity. Hence the ordered set optimalbeams can be expressed as

_(max,1) ^(I)=[B_(j) |j=0]={

₀,

₁}  (24)

The two stage capacity maximization include (i) diagonal search, (ii)global optimal search. The detailed operation of both diagonal searchand global optimal search are provided in FIG. 7.

FIGS. 5A-5B is flow diagram illustrating a method of selecting beam IDpairs associated with a transmitter antenna array and a receiver antennaarray, according to an embodiment as disclosed herein;

At step 502, the method includes generating a first matrix oftransmitter antenna ports and optimal beam ID pairs per receiver port.In an embodiment, the method allows the power and capacity computationalunit 232 to generate a first matrix of transmitter antenna ports andoptimal beam ID pairs per receiver port. At step 504, the methodincludes determining the sub-frame processing is high or not. If thesub-frame processing is high, then the method includes reading OFDMsymbols and other configuration parameters associated with transmitterantenna ports and optimal beam ID pairs, at step 506. Alternatively, ifthe sub-frame processing is low, then the method includes determiningagain the sub-frame processing is low, at step 508.

In an embodiment, the method allows the power and capacity computationalunit 232 to read OFDM symbols and other configuration parametersassociated with transmitter antenna ports and optimal transmit andreceive beam ID pairs for each and every receiver port.

At step 510, the method includes estimating channels associated with atleast one transmit port from a plurality of transmit ports associatedwith each receive port from a plurality of receiver ports. In anembodiment, the method allows the channel estimation unit 302 toestimate channels associated with at least one transmit port from aplurality of transmit ports associated with each receive port from aplurality of receiver ports.

At step 512, the method includes computing average power level of eachreceiver port for the at least one transmit port based on estimatedchannel. In an embodiment, the method allows the average powercomputational unit 304 to compute average power level of each receiverport for the at least one transmit port based on estimated channel.

At step 514, the method includes comparing the average power level ofeach receiver port with the predefined power threshold. In anembodiment, the method allows the average power computational unit 304to compare the average power level of reach receiver port with thepredefined power threshold.

If the average power level of each receiver port is greater than thepredefined power threshold then the method includes updating the firstmatrix having at least one transmit port and beam ID pairs associatedwith each receive port and maintain time stamp based on beam scanperiod, at step 516. In an embodiment, the method allows the averagepower computational unit 304 to update the first matrix having at leastone transmit port and beam ID pairs associated with each receive portand maintain time stamp based on beam scan period.

Alternatively, if the average power level of each receiver port is notgreater than the predefined power threshold then the method includesreading again the OFDM symbol and other configuration parametersassociated with transmitter antenna ports and optimal beam ID pairs, atstep 518 without updating the first power matrix.

At step 520, the method includes determining whether the OFDM symbolprocessing in symbol is over or not. In an embodiment, the method allowsthe capacity maximization unit 306 to determine whether the OFDM symbolprocessing in symbol is over or not.

If the OFDM symbol processing in symbol is over, then the methodincludes determining whether the sub-frame update is high or not at step520. In an embodiment, the method allows the capacity maximization unit306 to determine whether the sub-frame update is high or not.Alternatively, if the OFDM symbol processing in symbol is not over, thenthe method includes reading again the OFDM symbol and otherconfiguration parameters associated with transmitter antenna ports andoptimal beam ID pairs, at step 520.

At step 522, the method includes determining whether the sub-frameupdate is high or not. In an embodiment, the method allows the capacitymaximization unit 306 to determine whether the sub-frame update is highor not.

If the sub-frame update is high then the method includes computing fromfirst matrix of transmitter antenna ports and optimal beam ID pairs ofall receiver ports, at step 524. In an embodiment, the method allows thecapacity maximization unit 306 to compute capacity/SINR from firstmatrix of transmitter antenna ports and optimal beam ID pairs of allreceiver ports.

Alternatively, if the sub-frame update is not high then the methodincludes indicating the sub-frame level as low. In an embodiment, themethod allows the capacity maximization unit 306 to update the sub-framelevel as low.

At step 526, the method includes updating a second matrix of sets ofoptimal beam pairs based on Capacity/SINR computation and update timestamp of entries of the second matrix. In an embodiment, the methodallows the beam pair identification unit 308 to update a second matrixof sets of optimal beam pairs based on Capacity/SINR computation andupdate time stamp of entries of the second matrix.

FIG. 6 illustrates a matrix 600 for selecting a plurality of set ofoptimal beam ID pairs, according to a prior art as disclosed herein.

Consider an example scenario, having N_(T)=N_(R)=N_(S)=2, N_(TxB)=4 andN_(RxB)=3 which forms the matrix 600. A point ‘C’ associated with a beamID pair (Tx₀BID₃, Rx₀BID₀) is the capacity maximizing optimal point thatneeds to be estimated at the receiver 102. In conventional method, toidentify the optimal beam ID pair a diagonal search is performed acrossthe matrix 600 and the local maxima position ‘A’ is identified. However,during the diagonal search the point ‘C’ is not identified which theoptimal beam ID pair are not known. Therefore, to avoid this complexitythe FIG. 7 is proposed with the solution.

FIG. 7 illustrates a matrix 700 for selecting a plurality of set of theoptimal beam ID pairs, according to an embodiment as disclosed herein.Consider an example scenario of the N_(T)=N_(R)=N_(S)=2, N_(TxB)=4 andN_(RxB)=3 which form the matrix 700.

To identify the optimal beam ID pair a two stage capacity maximizationbased method is used as it is applicable only for N=1. The two stagecapacity maximization based method estimates capacity maximizing beampair set

_(max,1) ^(I) with reduced complexity. Hence the ordered set optimalbeams can be expressed as (24).

The two stage capacity maximization includes (i) diagonal search, (ii)global optimal search.

(i) Diagonal Search:

The diagonal search constrains the indices to compute (18) to thefollowing:

(q=s)=0,1, . . . ,N _(RxB)−1

(p=r)=0,1, . . . ,N _(TxB)−1  (25)

Ĥ_(c)(k, B_(j)) matrix is obtained as in (20) from the indices in (25)and substitute the result in (18). With these restrictions, the capacitymaximizing MIMO stream is obtained. By restricting the search space from(21) to these indices in (25), a local capacity maxima is arrived. Atleast one of the optimal beam-pairs A₀ or A₁ in (24) is present in this.Hence a local maxima is obtained such that

′_(max,1)={

_(p),

_(q)}={

₀,

_(q)} or {

_(p),

₁}  (26)

Owing to (25) this stage has a search space complexity ofN_(TxB)N_(RxB). To resolve the ambiguity in

′_(max,1) in (26) and arrive at the global solution, the next stage isrequired.

(ii) Global Optimum Search:

In this stage, the local maxima indices in (26) is used to arrive at theglobal maxima. Here as a first step the index A_(p) is kept fixed andA_(q) is varied across all possibilities. Hence the indices in (19) arevaried as follows

s=0,1, . . . ,N _(RxB)−1

r=0,1, . . . ,N _(TxB)−1  (27)

For each index in (26), Ĥ_(c)(k, B_(j)) as in (20) is computed andsubstituted in (18) and the optimal MIMO stream is obtained. Let themaximum capacity beam at this step be represented as

″_(max,1). Next the index set A_(q) is kept fixed and A_(p) is varied asfollows

q=0,1, . . . ,N _(RxB)−1

p=0,1, . . . ,N _(TxB)−1  (28)

For each of these indices, the capacity as in (18) is computed using thesame procedure as before. Let the maximum capacity beam at this step berepresented as

′″_(max,1). The maximum capacity beam-pair set of all these is chosen asthe optimal beam-ID pair stream.

_(max,1) ^(I)=arg max{

(

′_(max,1),

″_(max,1),

′″_(max,1))}  (29)

The complexity of the global optimum search stage is given byN_(s)N_(TxB)N_(RxB). The overall complexity of this scheme turns out tobe N_(TxB)N_(RxB)(1+N_(s)).

In FIG. 7 a point ‘C’ associated with a beam ID pair (Tx0BID3, Rx0BID0)is the capacity maximizing optimal point that needs to be estimated atthe receiver 102. To identify the optimal beam ID pair, first thediagonal search (i.e., step 1) is performed across the matrix 700 whichthe local maxima position ‘A’ is identified as per the equation (26).Further, the local maxima position ‘A’ is anchored to perform the globaloptimal search (i.e., step 2) as per (27) and (28). After performing theglobal optimal search (i.e., step 2) the global optimal position ‘C’ isobtained as per (28).

Unlike the conventional methods and systems, the proposed methodidentify the optimal beam ID pairs using both the diagonal search andthe global optimal search.

FIG. 8 is a graph representing a probability of correct detectioncomparison of the hybrid power and capacity maximization scheme with thereceived signal strength based scheme in presence of interference,according to an embodiment as disclosed herein.

In FIG. 8, a curve ‘A’ represents a capacity metric and a curve ‘B’represents a power metric. The BRS based channel estimation are used forboth power and capacity metric computations. The probability of correctbeam pair detection (Pcd) is plotted against SNR (Db) interferencescenario. Further, capacity metric based RF beam search techniqueoutperforms SNR/Power based techniques by >2 dB and gains expected toincrease under inter-cell/inter-BS interfering scenarios.

The embodiments disclosed herein can be implemented using at least onesoftware program running on at least one hardware device and performingnetwork management functions to dynamically control the elements. Theelements shown in FIG. 1 through 8 include blocks which can be at leastone of a hardware device, or a combination of hardware device andsoftware module.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the Meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modification within the spirit and scope of theembodiments as described herein.

What is claimed is:
 1. A method of selecting a plurality of sets ofoptimal transmit beam pairs and receive beam pairs in a wirelesscommunication system, the method comprising: estimating, by a receiver,channels associated with a plurality of transmit ports for each receiveport from a plurality of receive ports; and determining, by thereceiver, the plurality of sets of optimal transmit beam pairs andreceive beam pairs using: average power level at each receive port forat least one transmit port based on the estimated channel associatedbetween the transmit beam and receive beam pairs, a set of first powermatrices, wherein each first power matrix, from the set of first powermatrices, comprises at least one transmit port, transmit beam ID andreceive beam ID pairs associated with each receive port, wherein the setof first power matrices is formed based on the average power level ateach of the receive port, and a second capacity matrix formed based oncapacity maximization obtained from the set of first power matrices,wherein the plurality of sets of optimal transmit beam pairs and receivebeam pairs associated with each of the transmit and receive port isselected from the second capacity matrix.
 2. The method of claim 1,wherein the average power level at each receive port for at least onetransmit port based on the estimated channel associated between thetransmit beam and receive beam pairs is determined by: computing theaverage power level at each receive port for at least one transmit portbased on the estimated channel; and determining that the average powerlevel of each receive port for at least one transmit port meets a powerlevel threshold.
 3. The method of claim 1, wherein the capacitymaximization, obtained from the set of first power matrices, isdetermined based on one of maximizing a Signal-to-Interference plusnoise ratio (SINR) and a function of SINR associated with one or moresets of transmit beam and receive beam pairs associated with theplurality of receive antenna ports.
 4. The method of claim 1, whereinone or more sets of capacity maximizing beam pairs comprises of a numberof elements where each element is associated with a transmit portnumber, a receive port number, the transmit beam ID and the receive beamID pairs.
 5. The method of claim 1, wherein determining the plurality ofsets of optimal transmit beam pairs and receive beam pairs comprises:identifying at least one transmit beam ID and receive beam ID pairs bytraversing diagonally across a third matrix; anchoring the at least onetransmit beam ID and receive beam ID pairs identified in the thirdmatrix; performing a scan over at least one transmit beam ID and receivebeam ID pairs in the third matrix using the at least one anchoredtransmit beam ID and receive beam ID pairs; and determining, by thereceiver, the plurality of sets of optimal transmit beam pairs andreceive beam pairs based on the scan over the at least one anchoredtransmit beam ID and receive beam ID pairs.
 6. The method of claim 5,wherein the third matrix is determined based on the estimated channelassociated with at least one transmit port from a plurality of transmitports associated with each receive port from a plurality of receiveports.
 7. A method of selecting a plurality of sets of optimal transmitbeam pairs and receive beam pairs in a wireless communication system,the method comprising: estimating, by a receiver, channels associatedwith a plurality of transmit ports for each receive port from aplurality of receive ports; and determining, by the receiver, theplurality of sets of optimal transmit beam and receive beam pairs by:identifying at least one transmit beam ID and receive beam ID pairs bytraversing diagonally across a first matrix, anchoring, by the receiver,the at least one transmit beam ID and receive beam ID pairs identifiedin the first matrix, performing, by the receiver, a scan over at leastone transmit beam ID and receive beam ID pairs in the first matrix usingthe at least one anchored transmit beam ID and receive beam ID pairs,and determining, by the receiver, the plurality of sets of optimaltransmit beam pairs and receive beam pairs based on the scan over the atleast one anchored transmit beam ID and receive beam ID pairs.
 8. Themethod of claim 7, wherein the first matrix is determined based on theestimated channel associated with a plurality of transmit ports for eachreceive port from a plurality of receiver ports.
 9. The method of claim7, wherein at least one set of optimal transmit beam and receive beampairs from the plurality of sets of optimal transmit beam and receivebeam pairs comprises of a number of elements where each element isassociated with a transmit port number, a receive port number, thetransmit beam ID and the receive beam ID pairs.
 10. A receiver forselecting a plurality of optimal beam pairs in a wireless communicationsystem, the receiver comprises: a memory, a processor, coupled to thememory, and a beam pair selector, coupled to the processor, configuredto: estimate channels associated with a plurality of transmit ports foreach receive port from a plurality of receiver ports for transmit beamand receive beam pairs; and determine the plurality of sets of optimaltransmit beam and receive beam pairs using: average power level at eachreceive port for at least one transmit port based on the estimatedchannel associated between the transmit beam and receive beam pairs, aset of first power matrices, wherein each first power matrix, from theset of power matrices, comprises at least one transmit port, transmitbeam ID and receive beam ID pairs associated with each receive port,wherein the set of first power matrices is formed based on the averagepower level at each of the receive port, and a second capacity matrixformed based on capacity maximization obtained from the set of firstpower matrices, wherein the plurality of sets of optimal transmit beampairs and receive beam pairs associated with each of the transmit andreceive ports is selected from the second capacity matrix.
 11. Thereceiver of claim 10, wherein the average power level at each receiverport for at least one transmit port based on the estimated channelassociated between the transmit beam and receive beam pairs isdetermined by: computing the average power level at each receive portfor at least one transmit port based on the estimated channel; anddetermining that the average power level of each receive port for atleast one transmit port meets a power level threshold.
 12. The receiverof claim 10, wherein the capacity maximization obtained from the set offirst power matrices is determined based on one of maximizing aSignal-to-Interference plus noise ratio (SINR) and a function of SINRassociated with one or more sets of transmit beam and receive beam pairsassociated with the plurality of receive antenna ports.
 13. The receiverof claim 10, wherein one or more sets of capacity maximizing beam pairscomprises of a number of elements where each element is associated witha transmit port number, a receive port number, the transmit beam ID andthe receive beam ID pairs.
 14. The receiver of claim 10, whereindetermining one set of optimal transmit beam and receive beam pairscomprises: identifying at least one transmit beam ID and receive beam IDpairs by traversing diagonally across a third matrix; anchoring the atleast one transmit beam ID and receive beam ID pairs identified in thethird matrix; performing a scan over at least one transmit beam ID andreceive beam ID pair in the third matrix using the at least one anchoredtransmit beam ID and receive beam ID pairs; and determining theplurality of sets of optimal transmit beam pairs and receive beam pairsbased on the scan over the at least one anchored transmit beam ID andreceive beam ID pairs.
 15. The receiver of claim 14, wherein the thirdmatrix is determined based on the estimated channel associated with atleast one transmit port from a plurality of transmit ports associatedwith each receive port from a plurality of receiver ports and theassociated transmit beam and receive beam pairs.
 16. A receiver forselecting a plurality of sets of optimal transmit beam pairs and receivebeam pairs in a wireless communication system, the receiver comprises: amemory, a processor, coupled to the memory, and a beam pair selector,coupled to the processor, configured to: estimate channels associatedwith a plurality of transmit ports for each receive port from aplurality of receive ports, and determine the plurality of sets ofoptimal transmit beam and receive beam pairs by: identifying at leastone transmit beam ID and receive beam ID pairs by traversing diagonallyacross a first matrix, anchoring the at least one transmit beam ID andreceive beam ID pairs identified in the first matrix, performing a scanover at least one transmit beam ID and receive beam ID pairs in thefirst matrix using the at least one anchored transmit beam ID andreceive beam ID pairs, and determining the plurality of sets of optimalbeam transmit beam pairs and receive pairs based on the scan over the atleast one anchored transmit beam ID and receive beam ID pairs.
 17. Thereceiver of claim 16, wherein the first matrix is determined based onthe estimated channel associated with a plurality of transmit ports foreach receive port from a plurality of receiver ports and the associatedtransmit beam and receive beam pairs.
 18. The receiver of claim 16,wherein at least one set of optimal transmit beam and receive beam pairsfrom the plurality of sets of optimal transmit beam and receive beampairs comprises of a number of elements where each element is associatedwith a transmit port number, a receive port number, the transmit beam IDand the receive beam ID pairs.